Electrical sensing brush and method of making same



Aug. 30, 1955 R. w. BARNES 2,716,684

ELECTRICAL SENSING BRUSH AND METHOD OF MAKING SAME Filed Oct. 15, 1953 INVENTOR WQQM WFBW BY $13 ATTORN YS United States Patent Gffice 27,716,684 Patented Aug. 30, 1955 ELECTRICAL SENSING BRUH AND METHOD OF MAKING SAME Ralph W. Barnes, East Stroudsburg, Pa. Application October 15, 1953, Serial No. 386,267 4 Claims. (Cl. mil-J66) This invention relates broadly to the art of electrical sensing brushes and in its more specific aspects it relates to a sensing brush which may be used in electrical computer circuits; and the nature and objects of the invention will be readily recognized and understood by those skilled in the arts to which it relates in the light of the following explanation and detailed description of the accompanying drawings illustrating What I at present believe to be the preferred embodiments or mechanical expressions of my invention from among various other forms, arrangements, combinations and constructions, of which the invention is capable within the spirit and scope thereof.

Electric sensing brushes of the type with which I am particularly concerned may be used in computer circuits where an electric contact may be made through punched cards or the like as conventionally used in a great variety of business and computing machines.

Sensing brushes of this type may consist of a plurality of wires anchored or bound together by means of a sheath or ferrule from which they project. portant that the wires be maintained in a particular pattern or fixed relationship relative to each other in order that a good contact be made in the circuit. if this pattern is not maintained, the working or contact end portions of the wires will be splayed which is highly objectionable in most high speed electronic and computer circuits. It will be evident that in the assembly of the devices great care must be exercised so that the wires will be properly spaced and their pattern maintained, so that the groups of wires provide a multiplicity of contacts making for high unit contact pressures which break through any high resistant film which might accumulate on the surfaces contacted, in order to improve the reliability of the contact and the circuit in which the brush is used.

One of the major problems confronting the manufacturer of electrical sensing brushes of the type with which I am concerned lies in production problems. Prior to my invention it has not been possible to produce these at high speed and in a continuous operation without sacrificing the desirable accurate spacing and relationship of the wires within the ferrule so that the projecting portions thereof will be maintained in a pattern to make the proper electrical contacts when used in high speed computer and electronic circuits.

I have devised an electrical sensing brush which lends itself to high speed continuous production and which results in substantial economies in manufacture which were not possible in former brushes of which I am aware.

The electrical sensing brush which I have evolved consists of a ferrule which anchors and maintains the wires in proper relative arrangement and which is formed of stock of a solderable electrical conductive material such as brass. In maintaining the desired pattern for the wires of the brush to completely eliminate splaying of the contact ends, the Wires are arranged in groups It is im with a spacer and with means for confining the wires in proper relative positions. In prior ferrules used in this field the spacers and confining means have not been integral structures with resultant inefficiencies, difficulties and expenses of manufacture and assembly. These production difiiculties have been overcome by my ferrule which is produced as an integral unit, the spacers and confining means being formed in the stock. The advantages of forming the ferrule of a sensing brush of the general character of that involved in this invention as a unitary structure will be readily recognized when the method of assembly of the ferrule and the wires is explained and the speed and accuracy with which the device may be assembled becomes apparent.

Anyone skilled in this field will recognize that an efiicient brush of this nature must be so designed and produced that the wires will be clamped or otherwise fixed in a holder or ferrule so that they will maintain their relative positions. If this positioning is lost, proper contact will not be made and the utility of the device will largely diminish.

The ferrule of this invention has been devised to clamp about the contact wires to fixedly mount them in the ferrule against movement therein, and the method which I have evolved for forming the ferrule about the wires is such that it lends itself to high speed production making continuous operation possible. In producing the ferrule having the aforementioned highly desirable featurcs the stock of brass or other suitable solderable, electric conductive and pliable metal, which may be formed by an extruding, rolling, drawing or shaving operation, is provided with spacing means for the groups of wires and with weakened lines for later bending of the metal therealong to provide the confining and clamping means for the wires. Thus, as the stock is formed all the necessary spacing and confining means be provided and constitute integral parts thereof so that the ferrule with all its necessary attributes is a single unitary structure and the assembly thereof with and about the wires is greatly expedited and simplified.

In assembly the stock having the spacers and confining means formed therein may be cut into proper lengths, then sections thereof bent upwardly to form channels for receiving the groups of wires. The wires may then be laid into the channels and the next bending operation performed to fully envelop and clamp the groups of wires therein, whereupon a final crimping operation performed on the ferrule will keep the wires from being pulled longitudinally from the ferrule. As this description proceeds, it will be recognized that the production of electrical sensing brushes is greatly simplified by my invention which involves a sensing brush having only two parts; the ferrule and the wires. Prior art sensing brushes disclosed brushes having ferrules formed of several parts.

Many ferrules which have been used heretofore involved die cast ferrules which are objectionable from both a production and a service standpoint. A ferrule formed as described of a ductile or pliable metal has overcome the flash which is inevitable in a die cast brush, especially after the dies have had a small amount of Wear. My ferrule is made of a solderable material so that leads may be solder attached, if desired. This is impossible with a die cast brush. A brush of the nature of this invention would have better and more uniform electrical conductivity because the ferrule in a die cast brush being of die cast material is more porous and is made of high electrical resistant material with poor physical characteristics.

With the foregoing general objects, features and results in view, as well as certain others which will be apparent from the following explanation, the invention consists in certain novel features in design, construction, mounting and combination of elements, as will be more fully and particularly referred to and specified hereinafter.

Referring to the accompanying drawings:

Fig. 1 is a view in perspective of a length of stock from which the ferrule of my electrical sensing brush is fabricated.

Fig. 2 is a view in perspective of the electric sensing brush before completion of the fabrication thereof and after one bending operation has been performed thereon, and the groups of contact wires have been disposed in the formed channels in the ferrule.

Fig. 3 is a view in perspective of a completed electrical sensing brush.

Fig. 4 is a transverse section through the ferrule of a completed electrical sensing brush.

Fig. 5 is a longitudinal section through the ferrule of a completed electrical sensing brush.

In the accompanying drawings 1 have used the numeral 1 to designate in its entirety a length of stock, which may be formed by the aforesaid extruding, rolling, drawing, shaving or the like operation, from which the ferrule which is indicated generally by the numeral 3 is fabricated in a manner and according to the method to be hereinafter explained in detail. The stock consists of a length of solderable and electric conductive metal which is pliable so that it may be bent and folded about the contacting wires of the brush. Brass is a highly satisfactory metal for fabricating into the ferrule of my electrical sensing brush, and it may be extruded or otherwise formed into a strip of relatively thin gauge so as to be readily pliable but has sufficient rigidity in the finished article to withstand the strains to which it will be subjected in normal usage.

The ferrule forming strip 1 is formed with a central longitudinally extending spacer rib 5. Longitudinally extending grooves 7 and 7' are formed in the metal, one on each side of the rib 5 but in spaced relation thereto providing what l shall term channel sections 9 and 9. Further longitudinally extending grooves 11 and 11' are formed in the metal, one spaced outwardly from each groove 7 and 7' forming what I shall term wall sections 13 and 13 and closure sections 15 and 15'. As will be apparent as the description proceeds, the series of grooves provide weakened lines along which the metal is adapted to be bent in the fabrication of the ferrule, and it may be noted that the grooves 7 and 7 may be eliminated and the resulting ferrule will fall within the spirit and scope of my invention.

The stock 1 with the rib and the series of grooves is adapted to be cut into lengths of the size of the finished ferrule and either before or after cutting the stock is bent by any suitable bending means along the weakened lines provided by grooves 7 and 7'. This constitutes a step in the method of fabricating the ferrule and produces an article as illustrated in Fig. 2 of the drawings which, due to this first bending has the wire receiving channels 9 and 9' therein ready to receive the groups of contact wires.

When the stock is bent to form the article disclosed in Fig. 2, and as stated this first bending operation may be performed whether or not the grooves 7-7 are formed in the metal, the contact wires designated generally by the numeral 17 may be laid in the channels 9 and 9 of the partially fabricated ferrule, a portion of the wires projecting from the ferrule. Each sensing brush involves a plurality of contact wires 17 of any electric conductive material having some flexibility. I have found that splaying of the wire contact ends is eliminated and better contacts made if the wires are fixedly associated with the ferrule in groups, and in the particular example elected for illustration herein as one example from among many variations of which my invention is capable. I have shown two groups of wires 19 and 19', the group 19 being laid in channel 9 and the group 19' being laid in channel 9'. In this example I have shown eight wires in each group, and the wires of each group are laid in pairs, that is, one wire on top of another wire, all as clearly illustrated in the drawing. It will be understood that the spacer rib 5 of the ferrule spaces and separates the groups 19-19 and functions along with walls 13 and 13' to restrain the wires from lateral movement within the ferrule. The width of wire receiving channels is substantially equal to the total diameters of four wires so as to snugly receive the groups of wires. Reference to Fig. 4 of the drawings also shows that the height of walls 13 and 13 is substantially the same as the total diameters of two wires since the wires are stacked or positioned two deep in each channel.

When the two groups of wires have been laid in the channels as described, the ferrule and wires are in readiness for the next step in the production of the finished sensing brush. The unfinished ferrule with the wires in the channels is then bent along the grooves 1111 by any suitable bending mechanism to fold the closure members or sections 15--15' inwardly over the channels 9-9 and the contained wires and onto the spacer rib 5. The width of closure members 15-15 is slightly greater than the width of the channels so that the inner edges of the closure members will meet along the rib 5 as clearly illustrated in Fig. 2 of the drawings. It will be appreciated that the bending of the closure members, as described, confines the groups of wires within the channels against movement therein. A highly advantageous feature of my invention resides in the structure of the unfinished ferrule with the wires laid therein as illustrated in Fig. 2 of the drawings for the wires will not be displaced during the next bending operation due to the channel construction of the incompleted device, and due to the grooves 1111 which induce this final bending operation.

After the closure members 15 and 15' have been bent and folded down to close the channels and confine the groups of wires therein, a crimp or deformation 21 may be made transversely of the ferrule to lock the wires therein against being pulled longitudinally from the ferrule.

It will be recognized that production economies will be realized by my invention of forming the ferrule of a sensing brush from stock of a ductile metal having means formed therein for spacing and confining the groups of wires therein and also providing means for simplifying the method of assembly.

It will be recognized that while I have illustrated a sensing brush having two groups of wires, the brush may include a greater number of groups and still fall within the spirit and scope of this invention.

I claim:

1. An electrical sensing brush including a plurality of contact wires and a ferrule in which said wires are fixed to extend therefrom, said ferrule being formed of a unitary section of electrical conductive pliable material having a longitudinally extending spacer rib formed integral with the strip, a wall extending longitudinally of said section on each side of said rib in spaced relation thereto providing wire receiving channels between said rib and said walls, and means bendably attached to each wall and adapted to bend into position over and closing the channels and confining portions of the wires within the channels.

2. A generally flat strip of electrical conductive pliable material adapted to be fabricated into a ferrule for an electrical sensing brush, said strip having a longitudinally extending rib formed therein and a weakened bend line on each side of said strip, the bend lines being spaced from the rib and extending substantially parallel thereto, the strip adapted to be bent providing separated channels,

' walls and closure sections for clampedly receiving in the channels the end portions of wires of an electrical sensing brush.

3. The method of forming an electrical sensing brush including the steps of forming a strip of pliable electrical conductive material, forming a longitudinally extending rib on the strip, forming pairs of spaced longitudinally extending weakened bend lines on each side of said rib, bending the strip along the two bend lines adjacent the rib to provide channels for receiving contact wires, placing a group of contact wires in each channel and then bending the strip along each of the outermost bend lines to form closure members enclosing and clamping the groups of wires in the channels.

4. A strip of electrical conductive pliable material in generally flat form adapted to be fabricated into a ferrule 10 in which are clamped the wire ends of an electrical sensing brush, said strip being formed with a longitudinally extending rib therein, and having a longitudinally extending weakened bend line formed therein on each side of said rib and in spaced relation thereto providing wire receiving channels between the rib and said bend lines in the finished ferrule, and the strip being formed with a further longitudinally extending weakened bend line on each side of said rib and outwardly spaced from each of said first named bend lines, providing wall sections between said bend lines on each side of the rib in the finished ferrule and providing closure sections between said further bend lines and the longitudinal edges of the strip in the finished ferrule, and all of said bend lines being substantially parallel to said rib.

References Cited in the file of this patent UNITED STATES PATENTS 2,118,499 Durbin May 24, 1938 2,129,764 Hayes Sept. 13, 1938 2,429,585 Rogofi Oct. 21, 1947 

